This invention relates to an apparatus for navigating a vehicle in accordance with a course set before travel starts. More particularly, the invention relates to a system for outputting distance information in a navigation apparatus which provides guidance concerning travelling distance at suitable intervals.
Recent years have seen extensive development of vehicular navigation systems in which a course is preset before travel starts and the driver is given course information in accordance with the preset course.
When the driver is guided along the preset course, the conventional navigation apparatus displays a map on the screen of a CRT and superimposes the course on the map. In a case where the navigation apparatus guides the driver to an intersection at which a turn is to be made next in accordance with the preset course, the distance to this intersection is displayed numerically or in the form of a graph. Therefore, when a turn is to be made at an intersection using the conventional navigation apparatus, the driver observes the course displayed on the map to decide the next intersection at which the turn is to be made, or the driver looks at the numeral or graph display to ascertain the distance to the intersection where the turn is to be made, thereby determining the proper intersection.
In recently proposed navigation systems (for example, see the specifications of Japanese Patent Application Laid-Open (KOKAI) Nos. 59-68618, 59-196413, 60-202307, 60-218022), that arrangement is such that when the vehicle approaches an intersection at which the next turn is to be made, the driver is notified of information relating to this intersection by a voice track or visible display.
With the arrangement in which the map and the superimposed course are displayed, it is difficult to ascertain where the present position of the vehicle is on the course superimposed on the map and how far it is to a specific intersection. Moreover, since an intersection at which a turn is to be made next must be judged by looking at the course on the map, considerable attention is required in order to indentify the intersection, even if the intersection is nearby.
With the arrangement using numerals or a graph to display the distance to the intersection at which a turn is to be made, the driver cannot take his eyes off the road to view the display screen for an extended period of time while in the act of driving, and the driver therefore is constrained to glance at the display screen for short durations only. However, it is difficult to understand at once what is being displayed merely by a short glance at the screen.
Furthermore, with the system that notifies the driver of intersection information by voice or display when the vehicle has approached the pertinent intersection, no course guidance is given until this intersection has drawn near. Consequently, if the distance between one intersection at which a turn has been made and the intersection at which the next turn is to be made is great, absolutely no guidance relating to course is provided for an extended period of time and over a long distance. In such case the driver cannot verify whether the vehicle is travelling correctly in accordance with the preset course. The result is driver anxiety.